1. Field of the Invention
The present invention relates to machine for rehabilitating a track bed supporting a track comprising two rails, which comprises a machine frame supported on the track by undercarriages for movement along the track in an operating direction, the machine frame comprising machine frame parts being coupled together.
2. Description of the Prior Art
British patent No. 2,261,455 discloses a two-part machine for creating a protective layer on a subgrade. A coupling links a second machine frame part to a first machine frame part, and an undercarriage is arranged adjacent the coupling and is displaceable in a longitudinal direction of the machine frame to lengthen the track bed space from which the track has been lifted for performing the rehabilitation work. This space must be long enough to hold the bending curve of the lifted track rails within acceptable limits.
British patent No. 2,262,558 discloses another track bed rehabilitating machine comprising a machine frame whose ends are supported on the track by undercarriages. Two vertically adjustable crawler tractors are arranged at the front end of the machine frame to support the front end on the track bed while it is lifted with the track.
To lay a new track, French patent No. 2,538,525 proposes a machine having crawler tractors supporting a front end of the machine frame on the track bed while the rear machine frame end is supported by an undercarriage on the track.
It is a primary object of this invention to provide a machine for rehabilitating a track bed whose machine frame is supported on the track at its ends while providing an exceptionally long track bed space from which the track has been lifted for performing track bed rehabilitation work.
The above and other objects are accomplished according to the invention with a machine for rehabilitating a track bed supporting a track comprising two rails, which comprises a machine frame supported on the track by undercarriages for movement along the track in an operating direction, the machine frame comprising, in the operating direction, a first machine frame part, a second machine and a third machine frame part. A first coupling links the second machine frame part to the first machine frame part, a second coupling links the third machine frame part to the second machine frame part, and one of the undercarriages being arranged adjacent the first coupling. Two crawler tractors are spaced from each other in a direction extending transversely to the machine frame and connected to the second machine frame part, and drives connect the crawler tractors to the second machine frame part for vertically adjusting the crawler tractors.
Such a machine provides the possibility of substantially increasing the length of the track bed rehabilitation space at a minor increase in the construction costs. The two crawler tractors enable the second, central machine frame part to be supported on the subgrade subtending the track section limited by the two undercarriages supporting the machine frame ends on the track while this track section is lifted to a required height. Available machines with two-part machine frames may be readily retrofitted to insert a third machine frame part between the two machine frame parts.